NEW YORK ( TheStreet) -- Stocks on Friday extended losses spurred by Thursday's panicked selloff, easily making it the worst trading week of the year. The Dow Jones Industrial Average had the ninth-worst weekly performance in its history, losing 5.7%. It shed 140 points, or 1.3%, during the session to close at 10,380. The S&P 500 finished the session down by 17 points, or 1.5%, at 1111 and was 6.4% lower on the week. The Nasdaq finished the week 8% lower, having lost 54 points, or 2.3%, to 2266 on Friday. (The continued downturn came a day after the Dow lost 348 points, or 3.2%, to close at 10,520, its largest single-day fall since February 2009. The S&P 500 fell 38 points, or 3.2%, to 1128 on Thursday, while the Nasdaq lost 83 points, or 3.4%, to 2320.) Both the Securities and Exchange Commission and the Commodity Futures Trading Commission are sifting through trading data leading up to the chaotic selloff and said conflicting trading rules across different markets may be one possible cause. Friday's session was particularly rocky, with the Dow briefly venturing into positive territory but also losing as much as 279 points at one point to an intraday low of 10,241. "The market is ignoring the cyclical power of the recovery," said Federated Chief Equity Market Strategist Phil Orlando, adding that the fundamentals of Friday morning's April jobs report were "off-the-charts phenomenal" but that markets were having a hard time getting past Europe. "The fear is that since the (European Central Bank) has done nothing, the sovereign debt crisis in Greece will metastasize and jump the pond. There's a lot of concern about Europe going into the weekend with all these meetings coming up," Orlando said. "Anything can happen in the next couple of days, so no one wants to be long going into the weekend." On Sunday, the International Monetary Fund's executive board comes together to act on the fund's portion of Greece's financial rescue package, according to Reuters. Overseas, Asian markets reacted to Wall Street's staggering selloff . Hong Kong's Hang Seng lost 1.1%, while Japan's Nikkei shed 3.1%. In Europe, German lawmakers approved their share of a financial rescue package for Greece , and the U.K. has a hung Parliament after the Conservative Party won the most seats in the national election but fell short of a majority. The FTSE in London lost 2.6%, and the DAX in Frankfurt fell by 3.3%. "Markets have had a tremendous run-up since 2009, so some correction was expected," said Andrew Neale, partner and head of wealth management at Fogel Neale Partners. "But corrections usually take place over weeks or months -- not 30 minutes! That's very frightening for investors. People don't like to see so much volatility," "I think there's a high probability that that we could go a little lower and that volatility will continue until we find a level that people are comfortable with."